Is Weed Affecting Your Brain Long-Term? Study Suggests Dementia Risk May Be Sooner Than You Think

Canadian researchers analyzing over six million people discovered unexpected patterns that could fundamentally change how we view marijuana’s long-term safety profile. As cannabis legalization spreads across North America and usage climbs among populations once considered low-risk, scientists are uncovering connections between marijuana use and brain health that warrant serious attention. 

New findings emerge from one of the most extensive studies ever conducted examining cannabis-related health outcomes, raising questions about risks that may have been overlooked during legalization debates.

Massive Study Reveals Troubling Patterns

Researchers at the University of Ottawa examined health records from 6,086,794 individuals living in Ontario, Canada, between 2008 and 2021. Among study participants, 16,275 people required emergency department visits or hospitalizations related explicitly to cannabis use, representing approximately 0.3 percent of the total population examined.

Study participants averaged 55.2 years old, with 60.3 percent being male. Such demographics reflect growing cannabis use among middle-aged and older adults rather than traditional younger user stereotypes. Age patterns prove particularly significant since dementia risk naturally increases with advancing years.

Between 2008 and 2021, cannabis-related hospital visits increased dramatically across age groups. Adults aged 45 to 64 experienced a five-fold increase in emergency visits, from 10.16 to 50.65 per 100,000 people. Even more striking, adults 65 and older showed a 26.7-fold increase, jumping from 0.65 to 16.99 per 100,000 individuals during the study period.

Rising hospitalization rates correspond with cannabis legalization trends and changing social attitudes toward marijuana use. Such increases suggest greater usage among older populations or more severe health consequences requiring medical intervention.

Dementia Risk Numbers Tell Concerning Story

Study findings revealed stark differences in dementia diagnosis rates across different groups. Among individuals requiring cannabis-related emergency care, 5.0 percent developed dementia within five years. General hospital patients showed 3.6 percent dementia rates, while only 1.3 percent of the general population received dementia diagnoses during comparable timeframes.

Statistical analysis demonstrated that cannabis users faced 1.5-fold higher dementia risk compared to other hospital patients and 3.9-fold increased risk compared to the general population. Such elevated risks persisted even after researchers controlled for age, sex, mental health conditions, substance use, and chronic diseases, including diabetes and heart disease.

Dr. Daniel Myran, study co-author and assistant professor at University of Ottawa’s family medicine department, emphasized significant risk elevation. Cannabis users showed a 23 percent increased dementia risk compared to other hospital patients and a 72 percent higher risk compared to the general population after accounting for other dementia risk factors.

Interestingly, cannabis users demonstrated lower dementia risk compared to individuals hospitalized for alcohol-related issues, suggesting relative harm differences between substances. Alcohol users showed higher dementia rates than cannabis users, though both groups exceeded general population risks.

Why Pot Affects Memory and Thinking

Previous research established connections between cannabis use and short-term memory impairment, along with long-term brain structure changes. Active compounds in marijuana, particularly THC, affect brain regions responsible for memory formation and cognitive processing. Regular use may cause persistent alterations in neural pathways affecting learning and recall abilities.

Cannabis impacts brain development and function through interaction with the endocannabinoid system, which regulates various neurological processes. Heavy or prolonged use potentially disrupts natural brain chemistry, leading to cognitive difficulties that may increase dementia susceptibility.

Memory problems represent early warning signs of cognitive decline, potentially progressing to dementia. Cannabis users experiencing significant memory impairment may face a higher likelihood of developing more severe mental disorders later in life. Such progression could explain the elevated dementia rates observed in study participants.

Brain imaging studies show structural changes in chronic cannabis users, including reduced gray matter in regions associated with memory and executive function. Such alterations might predispose individuals to accelerated cognitive aging and increased dementia risk.

Rising Cannabis Use Among Older Adults

Cannabis legalization across multiple jurisdictions corresponds with increasing usage rates among older adult populations previously less likely to use marijuana. Older adults may turn to cannabis for medical purposes, including pain management, sleep assistance, or appetite stimulation, without fully understanding potential cognitive risks.

Age-related changes in drug metabolism may make older adults more susceptible to cannabis effects, including cognitive impairment. Slower processing of THC and other cannabinoids could lead to prolonged exposure and increased risk of adverse effects, including memory problems.

Older adults often take multiple medications, potentially interacting with cannabis compounds. Such drug interactions might amplify cognitive effects or create unexpected health complications requiring emergency medical care. Complex medication regimens are standard among older adults, which increases the risks associated with adding cannabis use.

Medical professionals may inadequately assess cannabis use among older patients, missing opportunities to identify potential cognitive risks. Healthcare providers need better training in recognizing cannabis-related health issues and counseling older adults about possible dangers.

My Personal RX on Leading a Healthy Lifestyle with Brain Health in Mind

Living well isn’t just about eating clean or hitting the gym—it’s about protecting the one organ that governs how we think, feel, and connect: the brain. Brain health is foundational to a vibrant, purposeful life, yet it’s often overlooked until something goes wrong. The good news? You don’t need to wait for warning signs. The small choices you make every day can nourish your brain, elevate your mood, and strengthen your resilience from the inside out.

1. Fuel your brain with healthy fats: Omega-rich foods like wild salmon, flaxseeds, and walnuts help build strong brain cells and protect against cognitive decline.
   
2. Prioritize your gut-brain connection: A thriving gut microbiome is linked to better focus, memory, and emotional balance. MindBiotic supports this critical axis with a powerful blend of probiotics, prebiotics, and Ashwagandha KSM-66.
   
3. Plan meals that nourish your mind: Meals rich in antioxidants, fiber, and healthy fats can lower inflammation and support long-term brain function. Mindful Meals is packed with gut- and brain-friendly recipes to keep your daily nutrition both smart and satisfying.
   
4. Keep moving, even in short bursts: Physical activity doesn’t just boost heart health. It increases blood flow to the brain, improves mood, and sharpens memory.
   
5. Get sunlight daily, but safely: Natural light helps regulate your sleep-wake cycle and boosts serotonin, the “feel-good” hormone. Morning walks are a great place to start.
   
6. Minimize processed food and added sugars: Highly processed foods and excess sugar are linked to poor mood and cognitive issues. Stick to whole, real foods as much as possible.
   
7. Practice stress resilience, not just stress relief: Instead of reacting to stress, build habits that make your brain more adaptable, like mindfulness, nature time, or breathwork.
   
8. Keep learning and exploring: Your brain craves novelty. Reading, puzzles, new skills, or even trying unfamiliar foods can keep neural pathways strong and active.
   
9. Sleep like it’s your job: Brain detox and memory consolidation happen during sleep. Aim for 7–9 hours of high-quality rest each night to support repair and renewal.
   
10. Think of health as a lifestyle, not a quick fix: No supplement or trend can replace consistent care. Focus on sustainable habits that support your gut, brain, and whole being, for the long run.

Sources: 

1. Myran, D. T., Pugliese, M., Harrison, L. D., Stall, N. M., & Webber, C. (2025). Risk of dementia in individuals with emergency department visits or hospitalizations due to cannabis. JAMA Neurology. https://doi.org/10.1001/jamaneurol.2025.0530 
2. Kuharic, D. B., Markovic, D., Brkovic, T., Kegalj, M. J., Rubic, Z., Vukasovic, A. V., Jeroncic, A., & Puljak, L. (2021). Cannabinoids for the treatment of dementia. Cochrane Library, 2021(9). https://doi.org/10.1002/14651858.cd012820.pub2